Give an account of the process adopted by Mendeleev for the classification of elements. How did he arrive at "periodic law"?

Explanation

To make the study of elements easy, Mendeleev tried to classify the elements on the basis of their chemical properties. He wrote the properties of each element on a separate card and tried to arrange them in different ways. He arranged all the 63 elements that were known in the order of their increasing atomic masses in horizontal rows (called periods) such that elements with similar properties were placed one below the other in the same vertical column (called groups). There were 7 periods and 8 groups in total. The classification was based on similarities in physical and chemical properties and the compounds formed by elements with hydrogen and oxygen i.e., formulae of hydrides and oxides). He noticed that elements of similar properties would repeat at periodic (regular) intervals (8th, 18th, or 32nd position). On this basis, he stated the periodic law as follows: "The properties of elements are a periodic function of their atomic masses." Hence, he named the table as the Periodic Table of elements.